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// A Boogie version of Elevator.asml (see Boogie/Test/inline/Elevator.asml)
var floors: [int]bool; // set of integer
var DoorsOpen: [int]bool;
var liftDoorOpen: bool;
var liftLevel: int;
var moving: bool;
var headingTo: int;
procedure Main_Error()
modifies floors, DoorsOpen, liftDoorOpen, liftLevel, moving, headingTo;
{
var i: int;
call Initialize();
while (true)
invariant !(liftDoorOpen && moving);
{
if (*) {
havoc i; call ButtonPress(i);
} else if (*) {
call MoveUp();
} else if (*) {
call MoveDown_Error();
} else if (*) {
call Stop();
} else if (*) {
call OpenLiftDoor();
} else if (*) {
call CloseLiftDoor();
} else if (*) {
havoc i; call OpenFloorDoor(i);
} else {
havoc i; call CloseFloorDoor(i);
}
}
}
procedure Main_Correct()
modifies floors, DoorsOpen, liftDoorOpen, liftLevel, moving, headingTo;
{
var i: int;
call Initialize();
while (true)
invariant !(liftDoorOpen && moving);
{
if (*) {
havoc i; call ButtonPress(i);
} else if (*) {
call MoveUp();
} else if (*) {
call MoveDown_Correct();
} else if (*) {
call Stop();
} else if (*) {
call OpenLiftDoor();
} else if (*) {
call CloseLiftDoor();
} else if (*) {
havoc i; call OpenFloorDoor(i);
} else {
havoc i; call CloseFloorDoor(i);
}
}
}
procedure {:inline 1} Initialize()
modifies floors, DoorsOpen, liftDoorOpen, liftLevel, moving, headingTo;
{
DoorsOpen := EmptySet;
liftDoorOpen := false;
liftLevel := 1;
moving := false;
headingTo := 0;
}
procedure {:inline 1} ButtonPress(i: int)
modifies headingTo;
{
assume floors[i];
headingTo := i;
}
procedure {:inline 1} MoveUp()
modifies moving, liftLevel;
{
assume !liftDoorOpen && liftLevel < headingTo;
assume !DoorsOpen[liftLevel];
moving := true;
liftLevel:= liftLevel + 1;
}
procedure {:inline 1} MoveDown_Error()
modifies moving, liftLevel;
{
//bug, should require that liftDoorOpen = false
// assume !liftDoorOpen;
assume liftLevel > headingTo && headingTo > 0;
assume !DoorsOpen[liftLevel];
moving := true;
liftLevel := liftLevel - 1;
}
procedure {:inline 1} MoveDown_Correct()
modifies moving, liftLevel;
{
assume !liftDoorOpen;
assume liftLevel > headingTo && headingTo > 0;
assume !DoorsOpen[liftLevel];
moving := true;
liftLevel := liftLevel - 1;
}
procedure {:inline 1} Stop()
modifies moving;
{
assume liftLevel == headingTo;
moving := false;
}
procedure {:inline 1} OpenLiftDoor()
modifies liftDoorOpen;
{
assume !moving;
liftDoorOpen := true;
}
procedure {:inline 1} CloseLiftDoor()
modifies liftDoorOpen;
{
liftDoorOpen := false;
}
procedure {:inline 1} OpenFloorDoor(i: int)
modifies DoorsOpen;
{
assume liftLevel == i;
DoorsOpen[i] := true; // DoorsOpen := DoorsOpen union {i};
}
procedure {:inline 1} CloseFloorDoor(i: int)
modifies DoorsOpen;
{
DoorsOpen[i] := false; // DoorsOpen := DoorsOpen - {i}
}
// ---------------------------------------------------------------
const EmptySet: [int]bool;
axiom (forall o: int :: { EmptySet[o] } !EmptySet[o]);
// ---------------------------------------------------------------
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